1. Field of the Invention
The invention relates to electrical cable couplers, also known as cable taps. More specifically, the invention relates to a cable coupler with low insertion losses and a variable coupling factor.
2. Description of Related Art
Many systems, for example in-building RF distribution systems or antenna arrays, utilize a trunk cable from which multiple connections, couplers, are made. For example, a trunk cable extending between several floors of a building may be coupled to supply/receive a signal to/from each floor. Each coupler applied to the trunk cable draws off a specified portion of the signal power present at the coupler location on the trunk cable. Therefore, successive couplers with a common coupling factor attached to the same trunk cable will receive a progressively lower signal level at each coupler location.
xe2x80x9cPiggy backxe2x80x9d cable couplers permit the diversion of a signal from a trunk cable to a second cable and vice versa, without requiring the attachment of connectors to the trunk cable. Conventional xe2x80x9cpiggy backxe2x80x9d co-axial cable couplers introduce a contact pin through an aperture created in the trunk cable""s shield/outer conductor that contacts the trunk cable""s center conductor. Creation of the aperture, without damaging the center conductor, is time consuming and normally requires a dedicated tool.
The contact pin of a conventional co-axial cable coupler creates a significant impedance discontinuity with mismatch loss. The mismatch loss, of a for example 10 dB coupler, combined with radiation and coupled energy losses, may create an insertion loss of up to approximately 1.5 dB with respect to the trunk cable, depending on the coupler, trunk cable type and the operating frequency. Where energy conservation is desired, or multiple couplers are required, the insertion loss from a conventional center conductor contacting co-axial cable coupler may be significant.
Couplers with low insertion losses exist. However, these devices require cutting the trunk cable at a desired insertion point, installing connectors at both sides of the break and insertion of the coupler, in-line. The separate structure of the coupler, required connectors and time-consuming installation procedure may cause this type of coupler to be undesirably expensive.
Competition within the coupler connector market has also focused attention on minimization of materials and manufacturing costs.
Therefore, it is an object of the invention to provide a method, apparatus and a kit for a coupler(s) which overcome deficiencies in the prior art.